Bought 05 XStar in April '12 with ~200 hours on 8.1L Indmar. I've had marine mechanic change oil every 50 hours, but I'm planning to do myself this weekend. Also planning to change spark plugs, oil filter, and filter in fuel pump.

I'm reasonably sure my stern drain plug is seized, so need to deal with that first. I know I had plug out over winter, but it didn't budge a few weeks ago with a wimpy wrench. I have a larger wrench this time, so hoping this will solve problem. If not, any other good tricks for removing stern plug?

Once plug is removed, I believe there's an oil drain hose attached to oil pan that's long enough to go out stern drain hole. If I'm wrong and this isn't oil drain hose (or if stern drain plug isn't removed), I will have a pump to manually suck oil out of block. I think oil drain tube is to the right of bilge pump in center of picture with brass end.

I have no idea what brand previous 40wt oil's were, but was considering AMSoil or Royal Purple even though still requires changing at 50 hours. Any oil brand suggestions for 8.1L?

Also planning to change filter and spark plugs. I have a freezer baggy and oil filter wrench to aid with replacing oil filter with ACDelco PF454. I have 8 pack of ACDelco 41-983 platinum spark plugs, dieclectric connector grease, anti-seize thread lube, and socket wrench. Is a torque wrench and spark gap tool necessary?